1. Description of the Prior Art
In the completion of oil wells drilled into the earth, perforating guns are employed for perforating the casing in the borehole for production purposes. A plurality of vertically spaced apart detonating devices are sequentially actuated to perforate the casing at a plurality of vertically spaced apart positions. The detonating devices are sequentially actuated by switches which are sequentially closed with each switch being closed by the explosive force caused by actuation of a preceding lower detonating device. The prior art switches in use, however, are unreliable.
2. Summary of the Invention
It is an object of the invention to provide a switch which is reliably closed by an explosive force.
The switch of the invention comprises a body means having an opening extending therein with two coaxial contacts located in the opening and electrically insulated from each other. Electrical leads are connected to the two contacts and extend out of the body means. A plunger means located in the opening of the body means is moved by explosive force to cause a third contact to engage the two coaxial contacts in the opening to form an electrical connection between the two leads.
In a further aspect, one of the contacts of said body means comprises a receiving contact located in the opening of said body means and which has a cavity formed therein with an opening leading to the cavity. The other contact located in the opening of said body means comprises an interior contact which is located in the cavity of said receiving contact. The third contact comprises a shuttle contact which is releaseably supported by the plunger means at one end thereof. Upon force being applied to the opposite end of the plunger means, the plunger means moves toward the receiving and interior contacts to a given position where its movement is stopped and the shuttle contact is released from the plunger means for movement into the cavity of the receiving contact for engaging both the receiving contact and the interior contact.
In another aspect, an electrical insulating, highly viscous material is located at least partially between the shuttle contact and the plunger means when the plunger means is located in its unactuated position for facilitating release of the shuttle contact from the plunger means upon the application of force to the opposite end of the plunger means.
In still another aspect, the plunger means comprises a plunger contact which releaseably supports the shuttle contact. When the plunger means is in its unactuated position, the end of the shuttle contact engages the receiving contact and an electrical connection is made between the lead of the receiving contact and the plunger contact by way of the receiving contact and the shuttle contact.